China had been pretty isolated in ancient times. Sure, there were a few northern tribes that kept invading the Hwang He plain, but they were the ones who were being influenced and absorbed by the Chinese. Is it possible for anyone from outside to influence China prior to 1400? Buddhism, an Indian religion, had (and still has) many followers, but it acquired a Chinese flavour much before the T'ang persecution of the Buddhists. Is it possible that if the Warring states period had lasted longer, that the south Chinese ethnicities would have been influenced by India, rather than China? The Nan Zhao kingdom of Yunnan was a heavily Tibetan influenced kingdom and for about 50 years ruled Sichuan. Is it possible that they would have been able to produce a different culture in south and west China, if they had been stronger? Or would it be possible for Japan to influence coastal China in ancient times? And finally, would it have been possible for the kingdoms of Champa and Dai Viet to influence Hainan and Guangxi at all? Or even the Khmer kingdom to gain control of Guizhou? All thoughts would be greatly appreciated.